题解 | #查找在职员工自入职以来的薪水涨幅情况#

解题思路：联结三张表，第一张表（employees）存储员工信息，第二张表（salaries）存储员工入职时的工资，第三张表（salaries）存储员工当前工资

SELECT p1.emp_no, p3.salary - p2.salary AS growth
FROM employees AS p1
JOIN salaries AS p2
ON p1.emp_no = p2.emp_no AND p1.hire_date = p2.from_date
JOIN salaries AS p3
ON p1.emp_no = p3.emp_no
WHERE p3.to_date = '9999-01-01'
ORDER BY growth